The Only Email Marketing Metrics That Matter

Focusing on the Right Retention Metrics

One of the biggest mistakes I see retention marketers make is obsessing over the wrong numbers. Too often, we end up optimizing metrics that look good on a dashboard but don't actually tell us whether the business is becoming healthier or not.

Today, I want to walk you through the KPIs I pay the most attention to and explain why I think they're a much better indicator of a successful retention strategy. But before I get into the KPIs that do matter, I want to touch on a couple that don't as much.

Open Rate: A Health Check

Number one, open rate. A lot of people obsess over this, but in reality, it's more of a health check than anything else. If you see that your open rate is dropping or it's really low, it can indicate some deliverability issues or damaged sender reputation. But outside of that, I don't spend that much time looking at it.

The reason is that Apple Mail Privacy Protection made open rates far less reliable than they used to be. I mainly use them for trends or identifying potential deliverability problems, but I would not consider them a true measure or indicator of a successful retention strategy.

Click Rate: A Supporting Metric

Click rate is kind of similar. This tells me whether people are actually engaging with an email or not, and it can also indicate some level of deliverability, which is useful. But clicks themselves don't generate revenue. Purchases do.

I've seen emails with super high click rates not generate many sales. Then you might have some that are a bit lower, but these are the ones that are actually hitting the target with the sales numbers. It's a supporting metric, but not necessarily a good business or retention metric.

Email Signup Rate: List Growth Versus Profitability

Now, email signup rate. This is probably the most overrated metric in all of retention. Brands love celebrating when they increase their pop-up conversion rate anywhere from 4% to 8%. But if those additional subscribers never become customers, then what did you actually accomplish?

I'd much rather have a pop-up that converts fewer visitors but attracts people who actually purchase and come back again, because growing your email list can be very easy, but growing a profitable one is much harder.

Subscription to Purchase Rate

Now, let's talk about the metrics that actually do move the needle. Number one, subscription to purchase rate. This is probably one of the most underrated metrics in all of email marketing. Not a lot of people know what it actually means.

Subscription to purchase rate measures the percentage of subscribers who eventually go on to make their first purchase. In my opinion, it's one of the clearest indicators of overall list health in your retention strategy because it doesn't just measure your emails. It measures the quality of people you're bringing into your ecosystem.

A lot of brands focus on growing their email list as quickly as possible. But if those additional subscribers never become customers, did the business actually improve? That's why I care so much about subscription to purchase rate versus signup rate, because it tells you whether you're attracting the right people in the first place.

A high subscription to purchase rate usually means you're bringing in visitors who are genuinely interested in what you sell, not just people looking for a discount before disappearing forever.

It also gives you insight into almost every part of your customer onboarding experience. If this metric is underperforming, the problem could be your pop-up. Maybe you're targeting the wrong visitors or leading with an offer that attracts bargain hunters instead of future customers.

It could also be that your welcome series isn't building enough confidence, your abandonment flows aren't recovering enough potential buyers, or maybe even your product pages aren't doing a good enough job of converting interest into action.

But the important thing here is that this metric forces you to think beyond email performance. Instead of asking, “How do I get more subscribers?” you're really asking, “How do I attract subscribers who can actually become customers?”

Because at the end of the day, I'd much rather have 10,000 subscribers where 30% of them become customers, as opposed to a list of 100,000 where only 3% ever make a purchase. That's the difference between building a big email list and building a valuable one.

30-Day Purchase Rate

Number two, 30-day purchase rate. This tells you what percentage of subscribers make their first purchase within the first 30 days of joining your email list.

I like this metric because it isolates your onboarding experience. It measures how effectively you're converting new subscribers while your brand is still top of mind. Subscription to purchase basically tells me how many subscribers eventually convert. But 30-day purchase rate tells me how efficiently we're converting them.

Efficiency is really important because, in general, if someone doesn't purchase within those first 30 days of subscribing to your brand, the likelihood of them ever becoming a customer starts to decline.

Imagine two brands that both convert 30% of their subscribers into customers. On paper, they might look identical, but Brand A converts most of those customers within the first two weeks, while Brand B might take six or seven months to get there. Which business would you rather own?

The faster you can convert a subscriber into a customer, the faster you generate cash flow, the faster you recover your acquisition costs, and the sooner you can start focusing on that customer's second purchase instead of still trying to earn their first.

Repeat Purchase Rate

The next metric I look at is repeat purchase rate. Acquiring a customer is expensive. Whether you're running Meta ads, Google ads, paying influencers, or whatever, you've already invested a significant amount to earn that first sale. The real profit comes when that customer comes back.

That's why repeat purchase rate is one of the most important metrics in all of retention. It tells you how effectively you're turning one-time buyers into loyal customers.

Now, this doesn't fall wholly on retention. There are a lot of variables that come into play in why a customer would ever buy again from your brand. But a healthy repeat purchase rate usually indicates that customers enjoyed their first experience. They like the product, the buying process was smooth, and your post-purchase strategy kept your brand top of mind.

On the other hand, if customers aren't returning, there's usually a reason. Maybe they don't know what to buy next. Maybe you're waiting too long to follow up. You're treating every customer the same instead of recommending products that are actually relevant to them. Or, to be blunt, it could also mean your product just isn't very good.

Repeat purchases increase customer lifetime value, improve profitability, and reduce your dependence on constantly acquiring new customers. This is truly where retention begins.

Time Between Orders

Number four, time between orders. This is one of the most overlooked metrics in ecommerce. Time between orders is basically exactly what it sounds like. It measures how long, on average, it takes a customer to come back and make another purchase.

Let's say, for example, your average customer buys every 120 days, or at least has 120 days between their first and second purchase. So you decide to implement better cross-sell emails, earlier replenishment reminders, a win-back flow, and start sending more relevant campaigns after that first purchase.

Suddenly, your customers are coming back in 95 days instead of 120. You didn't spend more on ads. You didn't increase website traffic. You didn't even need to grow your email list. All you did was help your existing customers buy a little bit sooner. When you do that across hundreds or thousands of customers, it really does start to compound and add up quickly.

This is why I always tell people that retention isn't just about increasing repeat purchase rate. It's also about reducing the amount of time between purchases.

That's where things like post-purchase flows, cross-sell emails, personalized recommendations, and even timely campaigns can become really important. The goal isn't to push people into buying something that they don't need. It's simply to stay relevant so that when they're ready to buy again, your brand is the first one they think of.

Sometimes the biggest opportunity isn't necessarily finding more customers, but helping the customers you already have come back just a little bit sooner.

Customer Lifetime Value

Number five, customer lifetime value. Customer lifetime value measures how much revenue the average customer generates over the course of their relationship with your brand.

The reason it's so important is that almost every retention initiative feeds into it. For example, a better subscriber welcome experience increases the number of first-time buyers

Lifetime Value as the Retention Scorecard

A stronger post-purchase journey might increase repeat purchase rate. Better segmentation and personalization might increase average order value and keep customers engaged. Reducing the time between orders creates more buying opportunities.

But none of these metrics exist in isolation. They're all working towards the same thing, which is increasing how much each customer is worth to the business. And when your LTV increases, everything else gets easier because you can afford to spend more to acquire a customer if you already know how much money you're going to make from them over time.

Your paid ads will become much more profitable. Cash flow will improve. Growth becomes more sustainable because you're generating more revenue from the customers you've already earned.

And that's why I think LTV is the ultimate scorecard for retention. If you're improving your onboarding, increasing repeat purchase rate, or shortening the time between orders, your LTV should naturally increase as a result. And if it isn't, then something in your retention strategy probably isn't working as well as you think.

Revenue per Subscriber

Number six is revenue per subscriber. I don't think enough brands pay attention to this one because everyone's obsessed with growing their email list. And as I've talked about in previous videos, more subscribers isn't always better, but more valuable subscribers are.

What revenue per subscriber measures is exactly what it sounds like: on average, how much revenue is each person on your list generating? It's one of the quickest ways to measure the overall health of your audience.

You can think about it this way. Let's say Brand A has 20,000 subscribers and generates 500,000 per year from email. Brand B has 100,000 subscribers, but they also generate $500,000 per year. These are pretty generic examples, but obviously Brand A is going to have a much healthier list because we know that every subscriber that we add onto that list, there's a higher likelihood that they're going to buy more.

And when this metric starts to increase, it's usually because you're attracting better subscribers, converting more of them into customers, and doing a better job of keeping them engaged over time. It's also a reminder that the goal isn't to build the biggest email list. It's to build the most valuable one.

Returning Customer Revenue Percentage

The final metric I look at is returning customer revenue percentage. This tells you what percentage of your total revenue comes from existing customers versus first-time customers.

I like this metric because it gives you a really good sense of how healthy the business is overall. If 90% of your revenue is coming from new customers every month, you're constantly starting from zero. You're relying on paid ads, influencers, organic content, or whatever acquisition channel you're using just to keep the business moving. It's a tough way to grow.

Granted, some businesses may be different. Some businesses are going to rely on acquisition a lot more than retention, but this is a really good indicator just to let you know exactly where you are in that cycle.

When a meaningful percentage of your revenue comes from returning customers, you know you've built a lot of momentum. Every month starts with customers who already know your brand, trust your products, and are much easier and cheaper to sell to than someone who's never heard of you before.

This doesn't mean you should aim for the highest returning customer revenue possible. Like I said, every business is different. A subscription brand, a consumable brand, and a furniture company are all going to have very different numbers for this. But what matters is the trend. If your retention strategy is working, you should gradually see more of your revenue being generated by customers you've already paid to acquire.

Measuring What Retention Is Really About

Those are the metrics I pay the most attention to when I'm evaluating a retention strategy. And notice that none of them have anything to do, really, with open rates, click rates, or how many emails you're sending each month. Those metrics can be useful for diagnosing individual problems, but they don't tell you whether your business is actually becoming healthier or not.

The metrics we talked about today do. They tell you whether you're attracting the right customers, converting them efficiently, encouraging them to come back, increasing their lifetime value, and ultimately building a business that's less dependent on constantly finding new customers.

That's really what retention is all about. It's not about sending more emails or having more automations than your competitors. It's really just about building systems that increase the value of every customer you pay to acquire. And if you focus on improving these metrics consistently over time, the revenue will follow.

E-commerce Retention Gap Calculator

And if you're not sure where your business stands today, then I highly recommend you check out the e-commerce retention gap calculator that my team and I created. It analyzes many of the metrics we talked about in this video, benchmarks your retention strategy, and estimates how much revenue you could be leaving on the table.

It's completely free. I'll leave a link in the description below for you to check it out. And if you like this video, please feel free to subscribe and like the video below.